Outcome of cephalosporin treatment of bacteremia due to CTX-M–type extended-spectrum β-lactamase–producing Escherichia coli

Abstract

The aim of the study was to analyze the outcome of different antibiotic treatments for bacteremia due to CTX-M–type extended-spectrum β-lactamase (ESBL)–producing Escherichia coli. In a prospective controlled clinical study from October 2002 to April 2005, 22 consecutive cases of bacteremia due to ESBL-producing E. coli with a ceftazidime-inhibition zone diameter of ≥18 mm were studied. The Etest method was used to determine the MIC values of cefotaxime, ceftazidime, imipenem, gentamicin, and ciprofloxacin against 22 isolates of E. coli. The polymerase chain reaction and sequencing analyses were used to determine the genotypes of the ESBLs. Of these 22 episodes, 7 were treated with ceftazidime, 8 were treated with imipenem/cilastatin, and 7 were treated with cefoperazone/sulbactam after detection of bacteremia. The demographic characteristics were comparable between the 3 groups. The treatment success ratio was similar (ceftazidime 85.7%, imipenem/cilastatin 87.5%, cefoperazone/sulbactam 71.4%, P = 0.637). Difficulties arose during treatment of peritonitis caused by CTX-M–producing E. coli bacteremia. Patients with bacteremia associated with urinary tract infection or biliary tract infection had a better chance of survival. All the 22 strains of E. coli produced CTX-M ESBLs (CTX-M-3, CTX-M-14, or CTX-M-27). The MICs of ceftazidime for 22 strains of E. coli were ≤8 μg/mL. All 7 patients who received ceftazidime survived, 6 of them were cured. Treatment in one patient with a ceftazidime MIC of 2 μg/mL failed because of abdominal abscess. Treatment with ceftazidime in vivo was effective against cases of CTX-M ESBL-producing E. coli bacteremia due to urinary tract infections and biliary tract infection when the MICs of ceftazidime were ≤8 μg/mL.